Test MP+DMB.ST+CSEL

AArch64 MP+DMB.ST+CSEL
{
0:X1=x; 0:X3=y;
1:X1=x; 1:X3=y;
}
P0          | P1                   ;
MOV W0,#1   | LDR W0,[X3]          ;
STR W0,[X1] | MOV W4,#4            ;
DMB ST      | CMP W4,W0            ;
MOV W2,#1   | MOV W5,#0            ;
STR W2,[X3] | CSEL W2, WZR, W5, NE ;
            | LDR W6,[X1,W2,SXTW]  ;
            | LC00:                ;
Observed
    1:X6=0; 1:X0=1;